Looking for advice…husband vomiting, stomach pain, wt loss

Hi!
I’m writing on behalf of my partner. He is 40 years old and had back surgery last year (titanium parts were added). A few months after surgery, he started vomiting… foam, dry heaving, vomit with food, sometimes mucous…whether he eats or not, this happens. He has stomach pain, especially in the morning. He’s had every test you can imagine (including a gastric emptying test), been to several GI docs & no one knows what it causing it. He has lost 55 lbs and it’s almost been a year. The only things that have helped are Xanax (but it makes him sleep most of the day) or thc gummies. A few docs have told him to quit the gummies, so he hasn’t had them for a month or so. He has an appointment at Mayo next month.
He’s so frustrated and depressed… he can barely enjoy life lately. He’s tried clean eating, several RX meds… just no relief. He hasn’t been working (he’s been on SSDI since before the back surgery) & he’d like to work again, but this illness seems to be all consuming.
I apologize if this has been addressed in other threads. I looked for answers that way, but it gets a bit overwhelming.
Thank you for any ideas or advice!